1. Field of the Invention
The invention relates to a coil fixing member of a rotating electrical machine, being a fixing member for fixing a coil that is disposed in a slot of a stator core, and to a rotating electrical machine that uses the coil fixing member.
2. Description of Related Art Japanese Patent Application Publication No. 2009-11063 (JP 2009-11063 A) discloses a stator of a rotating electrical machine. Coils that have rectangular wires are arrayed in a row and inserted into slots of the stator. Thereafter, wedges that are made up of an insulating resin or the like are inserted, along the axial direction, into openings of the slots, on the inward side in the radial direction. The slots are sealed by these wedges.
Japanese Patent Application Publication No. 2002-354731 (JP 2002-354731 A) discloses an alternator for vehicles. The alternator for vehicles has a rotor fixed to a shaft that is rotatably supported on a case, and a hollow-cylindrical stator iron core that is supported on the case, in such a way so as to enclose the rotor. The stator is configured by installing conductor wires on the stator iron core. The stator iron core has slots that extend in the axial direction. Two slots are provided for each phase and for each pole. The slots are side by side in a peripheral direction of the stator iron core. The conductor wires have a circular cross section and having an insulating coating. A radial dimension (d) of conductor wires and a circumferential dimension (L) of the slots obey a relationship 2d<L. In this alternator for vehicles, conductor wires having a circular cross section are fitted into the slots through an opening on the inward side in the radial direction. Wedges are fitted into respective slot openings. The wedges have a solid cylindrical shape, a hollow cylindrical shape, or a substantially cylindrical shape having a cutout, and are capable of deforming elastically.
In some instances, coils are wound on the stator in such a manner that coil end sections, which protrude from an end surface of the stator core in the axial direction, bulge toward the inner periphery of the stator core. In this case, it is difficult to insert the wedges into the slots along the axial direction, as disclosed in JP 2009-11063 A.
The deformable solid-cylindrical or hollow-cylindrical wedges disclosed in JP 2002-354731 A, by contrast, can be inserted into the slots through openings on the inward side in the radial direction. The outer periphery of the circular wedges abuts against, or engages with, protrusions on the inner periphery of the slots. As a result, it may be not possible to secure sufficient fixing force of the wedges against the slots. The above problem becomes particularly manifest when the coil wires that are inserted and disposed in the slots are rectangular wires having a comparatively large cross-sectional area. In such a case, there increases a force (spring-back force) that urges, inward in the radial direction, the coil wires in the slots, under the influence, for instance, of bending deformation of the coil end sections. As a result, the force that pushes the coil wires outward in the radial direction may become insufficient in such an instance. In consequence, coil wires may be disposed at positions, on the inward side in the radial direction, at which copper eddy-current loss is likely to occur on account of magnetic flux linkage from the rotor. The output efficiency of the rotating electrical machine may drop as a result.